Wheel dressing mechanism



WHEEL DRES S ING MECHANISM Filed April 6, 1944 5 Sheets-Sheet l.

91 J v a m I QL Aug. 24, 19. 8- -.J. cs, HARPER ET AL WHEEL DRESSING MECHANISM 5 Sheets-Sheet 2 Filed April 6; 1944 Elma/Mow James 6.]farfie7'arzd Cecil W Aug. 24, 194. J. G. HARPER ET AL 2, WHEEL DRESSING MECHANISM Filed A ril 6, 1944 v 5 Sheets-Sheet 4 Jamas djfazperand Cecil WWW,

1948. J. G. HARPER E T AL. 2 1

WHEEL DRESSING MECHANISM 7 Filed April 6, 1944 4 5 Sheets-Sheet 5 130 I, Qj W '72? 704 James 6.1-! and Cecil W Hqpkirzs,

Patented Aug. 24, 194-8 WHEEL DRESSING MECHANISM James G. Harper and Cecil W. Hopkins, Waynesboro, Pa., assignors to Landis Machine Company, Waynesboro, Pa., a corporation of Pennsylvania.

Application April 6, 1944, Serial No. 529,810

This invention relates to wheel dressing mechanism and more particularly to a mechanism of that type which is employed'in thread grinding machines for the purpose of dressing or truing the profile of the abrasive thread grinding wheel.

It is one of the objects of our present invention to provide a dressing or truing mechanism having certain novel features of construction which may be used to advantage in either the automatic or hand operated type of dressing mechanism.

It is another object of the invention to provide improved means for controlling the movements of the dressing tool carrying slide in parallel relation with the grinding wheel axis and alsoperpendi'cularlythereto, whereby a rapid and accurate dressing or'truing of the Wheel profile is obtained.

It is an additional object of our invention to provide a novel mounting and arrangement of the tool slide and the carriage for substantially frictionless relative movement inangularly related planes and with greater stability and accurate control of the movement of the wheel dressing tool.

A still further object of our invention is to provide a wheel dressing mechanism in which the several parts are of simple structural form and are cooperatively associated in a compact organization sealed within a housing of minimum dimensions.

Among the subordinate objects of our invention are the provision of a simple and positively operating means for the tooli slidecarriage, a novel mounting and arrangement of the template-and stylus with respect to the tool slide for controlling theperpendicular movement thereofwith respect to the wheel axis, and means for adjustably mounting the wheel dressing unit upon the dresser slide of a grinding machine for bodily movement therewith to and from operative relation with the-grinding wheel.

Other practically important features of our present invention will become evident from the following detaileddescription ofthe several practiCal embodiments thereof-illustrated in the accompanying drawings, in which similar reference characters designate corresponding parts throughout the several views, and wherein:

Figure 1 is a horizontal sectional view' taken substantially on the line l--l of Figure 2, illustrating an automatic type of our improved wheel dressing mechanism Figure 2 is a transverse vertical section taken substantially on the line 2-4 of Figure 1;

Figure 3 isa longitudinal vertical section, taken substantially on: the line 3'-3'- of Figure l;

6 Claims. (CL 125-11) Figure 4 is a transverse sectional view taken substantially Ontheline 4-4 of Figure I; f I

Figur 5 is a horizontal sectional view, taken substantially on the line 5-5 of Figure 3;

Figure 6 is a detail plan View, certain parts thereof being shown in section;

Figure '7 is a horizontal sectional view, taken substantially on the linel-l of Figure 9, the latter view being placed 90 out of true position, and illustrating a manually operable embodiment'of our invention;

Figure 8 is a vertical sectional view, taken substantially on the line 8-8 of Figure 7;

Figure 9 is a similar sectional view'taken substantiallyon the line 99 of Figure '7; and

Figure 10 is a detail vertical section, taken substantially on the line Ill-l0 of Figure'l.

With further reference to the drawings, and for the present more particularly to Figures 1' to 6 thereof, we have therein illustrated a typical structural example of the novel features of our present invention as embodied in an automatic type of wheel dressing mechanism. As therein shown, the several cooperatively related parts of this mechanism are enclosed within a substantially rectangular housing, comprising the body I 0, opposite ends of which are closed by the cover plates H and I2, respectively, detachablysecured to the body wall by the bolts or screws I3 and HI, respectively. The top of this housing is similarly closed by' the cover plate: l5 detachably' secured to the housing wall by the screws IS.

The bottom wall of the housing body in internally thereof is rabbeted along opposite sides thereof, as at H, to provide seats for the longitudinal guide members, 18 and [9; respectively, which are substantially coextensive with the internal longitudinal dimension of the housing. The guide member i8 i rigidly secured to the housing wall by a plurality of screws 20; The other guide member i9 is slidably heldupon its seat l'l by the screws 21? extending through. elongated openings 22 in the bottom wall of the housing body. Thus, it will be understood that this member [9 may have limited movement with'respect to the member I'B transversely of the housmg.

Between the guide members. l8 and ill the tool slide carriage 23 is positioned. Intermediate of its opposite ends this carriage is cut away or recessed, as at 24, for a purposeto be later described, said recess opening upon one'longitudinal edge of the carriage plate which isopposed to the guidemember [9. The inner sid faces of the guide membersrl8 and i9; and'the opposed edge faces of the carriage plate 23 are longitudinally grooved as at 25 and 26, respectively. These grooves provide race-ways for the anti-friction balls 21 held in spaced apart relation by the retainer 28 between member l8 and the carriage. Similar anti-friction balls 29 and retainers 3B are interposed between the .other'gui-demember l and the carriage 23 at each side of the recess 24 in the carriage plate. These anti-friction bearing units provide adequate supports, sustaining the carriage plate 23 with respect tothe housing wall and guide members l8 and 19 for substanat the upper end thereof the guide member 55 is tially frictionless movement longitudinally of the housing. Longitudinal movement of the retainers 28 and 30 is restricted and limited by the stop pins 38 suitably embedded in the guide members l8 and I9. r r v The guide member i9 is provided with longitusecured by screws 57. The tool carrying slide 58 is positioned in a vertical plane between this guide member and the carriage plate 23, upper and lower anti-friction balls 59 and 60, respectively,

1 held in the retainers BI and 62, being interposed dinally spaced recesses 32 opening on the outer side face thereof and prings 33 in these recesses, bearing against a side wall of the housing, constantly urge the member, l9 and carriage plate 23 transversely toward the member l3, thu insuring proper automatic adjustment to compensate forwear.

The carriage plate 23 is provided with a longitudinally extending bore 34 in which the coiled spring 35 is received. One end of this spring has bearing engagement with a cylindrical pin 38 slidably engaged in one end oi-th-e bore 3'4 and having a convex outer end in bearing contact with the end closure or cover member l I of the housing. A tension adjusting screw 31 for said-spring is threaded in the other end of the bore 34. It will therefore be understood that the spring 35 yieldingly urgesthe carriage plate 23-longitudinally in one direction withrespect to the guide members l8 and I9.

A vertically disposed bushing 38-is suitably secured in the dresser slide of the grinding machine, which is partially illustrated at '39 in Figure 3 of the drawings. The upper end of said bushing is received in the opening 3 8' in the bottom wall of the -housing ii]. A shaft 40 journalled in the bushing 3'8 has a reduced upper. end portion 4! to which the pinion 42 is keyed or pinned as .at 43. This pinion is located in the recess 24 of the carriage 23, and at its upper end isconstantly engaged with the teethof a rack 44 securedby screws 45 in a recess 45 in the upper face of the carriage plate 23. Back lash or lost motion between the teeth .of pinion 42 and rack 44 is eliminated by the action of the spring 35. Longitudinal movement of the carriage 23 in each direction is limited by the stop pins ll-suitably fixed in the bottom wall of the housing.

While any suitable means may be provided for automatically imparting oscillatory rotary motion to the shaft 40 and pinion 42 in the operation of the thread grinding machine, for this purpose we provide the simple'arrangement shown in Figures 3 and 5 ofthe drawings in which the lower end of the shaft 4il-is secured to one end of a lever 41' having a longitudinal guide channel 48 for the roller 49 mounted on the end of a crank arm 59 secured to the power driven shaft 5!. It will be obvious that, in the rotation of shaft 5! and the orankSO, oscillatory motion i transmitted to the pinion'42 so that-the carriage 23 will-be alternatelymoved longitudinally within the housing H! in opposite directions. These movements of the carriage are limited by the pins 4! contacting the sides of the recess'24 in the carriage 23. Upon the upper face of the carriage plate 23 an L-shaped bracket :52 is rigidly mounted.

between said slide and the member 56 and carriage plate 23. Longitudinal movement of the ball retainer 6! is limited by the stop pins 63 fixed in the member 55 and slide 58 and longitudinal movement ofthe retainer 62 is limit-ed by thestop pins 64 fixed in the tool slide.

A pin 55 is fixed to the tool slide 58 and projects transversely therefrom into the slot 66 in bracket '52. This projecting end of the pin has a fiat side face Bl to which one end of .a guide rod 58is fixed. This rod extends in parallel relation to the slide 58 into a bore 59 in the bracket which communicates at one end with slot 56. A spring ill surrounding rod 68 bears at one of its ends against the face 51 of pin 55 and at its other end against the tension adjusting screw H threaded in the outer end of bore '69. It will thus be understood that the spring "H1 yieldingly resists transverse movement of the tool slide 58 in one direction with respect to the carriage plate 2 3 and urges said tool slide toward the periphery of the grinding wheel, indicated at 12.

I To the inner face of the rear wall of housing l0, above the member IS, a bracket 13 is rigidly attached, as by screws 14. The horizontal arm l5 of this bracket has a recessed upper face 16 to which is rigidly secured the template barll extending from said bracket longitudinally of the carriage 23 and into a slot or recess 79 in the inner or rear end of the tool slide 58. This end of the template bar is formed with a replica 80 of the profile outline to be produced upon the peripheral face of the grinding wheel 12, which in thepresent instance is represented by. a thread outline of 'Whitworth form. A stylus 8|, secured to the rear end of the slide 58 by screw 82, also extends into the recess 19 and is constantly urged into cooperative engagement with the part 80 of the template bar by the action of the spring 10.

The outer end of the tool slide 58 is movable through an opening 82 in the side Wall of the housing l0 and is formed with a reduced neck portion 83 upon which the dressing tool holder 84 is detachably mounted. Preferably, this holder has a groove 85 to receive the-rib 83 on the end face of the neck 83 to prevent pivotal movement of the holder with respect to the attaching screw 86. The wheel dressing tool 8'! is detachably secured in holder 84 in conventional manner by means of the screw 88. The opening 82 in the housing wall 'is completely closed and sealed by means of a flexible diaphragm 89 of leather or other suitable material. An air and dust tight connection between the outer edge portion of this diaphragm and the housing wall is effected by means of the clamping ring 90 and screws 9| which are threaded into the wall of 5"; thehousing and detachably secure the diaphragm-thereto; The neck 8'3-of-sli'de 5ilis provided with the groove 92 to receive the inneredge of the'diaphragm 82 which issecurely held in airtight engagement with the walls ofsai-d groove by the clamping ring 93-; 'Thus, it will be seen that the interior ofthe housing I and all parts of the mechanism contained therein to control movement of 'the tool 84 are-completely sealed so that grinding Wheel dust or-other' foreign matter cannot find its way to the interioring Hl'at one endthereoi" by the screws 95 and is formed With a slot 96 to receive the project'- ing end of a pin 91 fixed in the end of theslide 39. Aligned relatively adjustable screws-9B are threaded in the bracket" 94" and bear against the projecting end of pin 91' at diametricallyopposit'e points. By properly adjusting these screws 98, the housing lflandthe entire dressing mechanism may be pivotally moved about the axis of pinion 42- to position the path of reciprocating motion of carriage 23' in accurate parallel relation with the rotative axis of the grinding wheel 12 and the slide 58 in exact perpendicular relation to said axis.

In the operation of the mechanism'above ole-- scribed, it will be apparent that, in the rotation of the crank 55, pinion 42, coacting with the rack 44 in its oscillating motion, will reoiprocate the carriage plate 23 in a direction parallel to the axis of the grinding wheel 12, and the tool slide 58 will be similarly moved as a unit with said carriage. As the dressing tool 81 is thus moved across the face of the grinding wheel 12, stylus 8| fixed to slide 58 is moved in contact with the thread outline- 80 of the template bar 1'! fixed to the stationary bracket number 13, and, in conjunction with the action of spring 70, produces independent reciprocatory movement of the tool slide 58 transversely across the carriage 23 simultaneously With the movement of said carriage, and in a direction perpendicular to the axis of the grinding wheel 12.

Such compound movements of the dressing tool reproduce the outline contour of part 8!] of thetemplate bar upon the peripheral face. of the grinding wheel.

It is to be particularly observed that We provide. anti-friction supporting means for the tool slide extending'entirely across the carriage. plate 23. Thus, maximum stability in the mounting. of said tool slide is obtained and all possibility of angular displacement thereof relative to. the carriage which would result in an inaccurate dressing operation of the tool 81, is precluded, In other Words, the stylus 8! on the tool slide 58 is at all times in accurate alignment with the outline of the template part 80 in the movement of. the carriage plate 23. It will, further be appreciated that our invention provides a wheel dressing mechanism of this kind comprisiIlg a very compact assembly of a minimum. number of mechanical parts. of simple structural form, cooperatively associated for accurate func- To this end, a bracket 6. tional operation within an enclosing. housing? of minimumdimensions. l

'We have'also embodied certain of: the novel; features above. described a manually Opereable type of wheel dressingmechanism which. will! now be described; with reference to: Figures 7 to 10 of the drawings.

In one practical embodiment of this: form of our invention. thedresser mechanismis mounted upona supporting.- member H101, suitably fixed: to: avertically: disposed: stationary I member org-a: thread. a grinding machine (not: shown). This: support I00 is provided on one side thereof, with the malepart NH of aconventional dovetail slide assembly" to coact with the female-part N3. of said assembly formed. on the slide H12. Between; one of theinclined faces of the part l:0l= and the opposing inclined face ofetheslide: I102 the gib; IM is retained in position and tightened; against. the part EM, as wearmay necessitata, by means of the, set; screws Rotational displacement ofthese screws from adjusted posi-- tiorr is prevented; by the lockingv screws i06 also threaded: in the slide Hi2; Thus move-mentorthe slide N12 is constrainedto a direction which: isexactlyperpendicular to the axis of the grind ing wheel M l, shown in Figure '7.

In the end of the support lmkremote from the Wheel :01, a bearing; H18 isprovided'. for an ad; justing screw orshaft H19; This-shaft has: a threaded section H6 on which the-traveling nut H! is movable. A collar ltzfixed 13118;- shaft I09 by pin H3- has bearing. engagement against the inner side, of the shaft bearing H18 and a handwheel: I I4 secured tothe outer endof said shaft in rotative contact with the outer face of the bearing Hi8, b means of a. nut" H5; is. held; against rotative-movement on the. shaft by -thekey H5 fixed to said shaft andengaged in the groove H! of said handwvheel. This handrwheeli is provided with a duct lzlt throughwhich lubrieating oil may be supplied to: the hearing I08; the outer end of the duct being normally closed by the; screw I I9;

The nut: H4 is formedrwithr a lug or projection" I 20 onone' side thereofi closely fitting: within an opening I21 in the slidel 02.. The nut H1 is. also'provided with a transverse opening IZZ- which extends through the-projection. tZiltoreceive the screw I 23, the enlarged head otwhich has bearing engagement on the internal shoulder I24 of the projection 5-29, the threaded shank of said screw extending through theopening IZI in the slide to secure apart of the mounting for the dressing mechanism in attachedposition on the face of the slide, as will presently bedescribed. It will thus be seen that rotation of the hand wheel. I M will rotate-shaft Hill and cause thenut i H and slide A82. to move relative to the support H38 in a direction perpendicular to. the axis of: the grindingwheel M11;

Upon the peripheral face of the wheel H4 suitable. scale graduations l-Z-dare delineated. to cooperate with an index mark 121 on the end face of a pin l2ii fixed in. the bearing not. Thus, thenecessary degree ofrotation of the Wheel-I M- for a predetermined linear movement of the slide I92 can be accurately gauged.

To-the outer side face of the slide Iii-2, laterally spaced aparthousing and guiding members I23 and I29, respectively, are attached. The memeber !.28 is rigidly secured to the slide by means of the screws I30, while the. screw I23 serves as. acommonmeans for attachingv the otherof saidguide members I29. and the nut IH, toslidetflrZr.

'A quadrant-shaped part I3I is secured in a recess I33 in the housing member I29 and is preferably symmetrical in external contour with member I29, as shown in Figure 9. I .The part I3I is formed with a longitudinal recess I34 to receive the template bar I35 which is rigidly fixed to the member I29 by the screws I36.

The members IZB'and I29 are assembled upon the slide I 02 with their opposed faces in accurately mating contact with each. other by the tongue or rib I31 on the member I29-fitting within the groove I38 formed in the opposing face or the member I28. Thus, oppositely inclined guiding surfaces I39 and I40, respectively, for the tool slide carriage, to be presently described, are accurately located relative to each other.

The tool slide carriage includes an elongated part I42 of substantially rectangular form in crosssection, the respective faces of which have sliding contact with the guiding surfaces I39 and I40 of'the supporting and housing members I28 and I29. The recess I43 formed in the face of the slide I02 constitutes an extension of these guiding surfaces. The outer end of the slidable part I42 of the carriage is integrally formed with a housing member I44 for the tool carrying slide I45, the members I46 and I41, detachably secured to the member I44 in any suitable manner, completing the housing structure.

The part I42 of-the carriage is provided with a central longitudinal bore I48 and a tension spring I49 within this bore has one of its ends connected to a pin I50 seated at its ends in notches or recesses II in the housing member I44.

The other end of this spring extends through an opening I52 in the slide I02 and is secured to the pin I53, the ends of which are seated in notches or recesses I54 in the rear face of the slide. 'It will be evident that the spring I49 yieldingly urges the carriage slide I42 inwardly between the members I28 and I29 toward the slide I02 to a normal position.

The rectangular carriage slide I42, at the junc ture of two adjacent side faces thereof, is formed with a recess I42 and a plurality of rack teeth I54 on the base wall thereof, have cooperative engagement with the teeth of a pinion I55, formed upon or fixed to the shaft I56, journalled at one of its ends in the vertical bore I51 formed in the guide member I28. This shaft is rotatably supported in the bushing I58 having a driving fit within the opposite end of the bore I51. The inner end of this bushing abuts one end of the pinion I55 and the other end of said bushing is diametrically enlarged to provide a shoulder I59 having abutting contact against the face of the member I28. The end of the shaft I56 extends beyond the bushing I58 and has a collar I60 pinned thereto by the taper pin I6I formed on the end of the shaft operating handle I62. The inner end of the collar I60 has a cylindrical recess I63 to receive the enlarged end of the bushing I58, the wall of this recess extending over and covering the felt ring or other sealing material I64 contained in the peripheral groove I65 formed in the enlarged outer end of the bushing I58. Thus leakage of lubricant contained within the mechanism will be prevented.

As shown in Figure 8 of the drawings, guide members I66 and I61 are secured to the carriage part I44 above and below the slide I45 by suitable screws I68, and also constitute parts of the housing structure which completely encloses the slide with the exception of the reduced forward end I69 thereof which projects through opening I in housing part I44 and carries the dressing tool IN. This tool is detachably fixed to the slide by collar I12 surrounding'the said slide and carrying a set screw I13 to engage the shank of the tool Ill and immovably fix the same against the wall of recess I14 in the slide.

In order to exclude grit and dust from the slide housing, a sealing member I15 of any suitable material may be attached to the housing part I44 in closely contacting relation with surfaces of the slide end I69 at the opening I10.

Members I66 and I61 and slide I45 are grooved to receive the rolling elements of anti-friction units I61, similar to those shown in Figure 2 of the drawings.

The carriage part I44 rearwardly of the slide I42 is provided withan opening I11 through which the template bar I35 fixed to the member I29 extends. The rear end of the tool slide I45 is recessed, as at I18, to receive the end of the template bar. In this case the outline part I19 of the template, corresponding to the part in Figure 6, is detachably secured to the template bar by means of a set screw I80.

The stylus IBI which cooperates with the outline part I19 is fixed to the rear end of the tool slide I45 by means of the collar I82 and set screw I83. The slide I45 is also provided with a pin I84 longitudinally extending rearwardly therefrom and slidably supported in the end of a tubular member I63 which is suitably fixed to the housing cover member I46. A spring I85 is interposed between thepin I84 and the tension regulating screw I85 which is threaded in the outer end of the tubular member I03. This spring exerts a light sensitive pressure force against the rear end of the slide to maintain the stylus I8I in operative contact with the outline part I19 carried by template bar I35.

For the purpose of excluding the entrance of grinding wheel dust and other foreign matter, we preferably attach the edges of a flexible boot or a diaphragm I81 in sealing engagement with the members I20 and I29 and the part I44 of the tool slide housing.

From the above description the construction and operation of this manually operable type of our invention will be readily understood. Upon rotation of the wheel or knob II4, the slide I02 with the dresser mechanism mounted thereon is moved as a unit on the support I00 to position the dressing tool I1I in operative relation to the periphery of the grinding wheel I10. The handle or lever I62 is then manually operated to oscillate pinion I55. This pinion cooperating with rack teeth I54 moves the tool slide carriage relative to the fixed parts I23 and I29 and template bar 35 in one direction against the resistance of spring I49, to cause the dressing tool I1I to traverse the profile of the grinding wheel I01 in a path parallel toaxis of said wheel. Simultaneously with this movement of the slide carriage, the stylus IBI coacts with the relatively fixed thread outline part I19 and moves the dressing tool "I perpendicularly of the grinding wheel axis to accurately reproduce said outline form upon the profile of the grinding wheel.

It will be observed that the fundamental features of our invention may be embodied in either the automatic or hand operated type of wheel dressing mechanism in a very compact, spaceconserving assembly to operate with maximum efficiency and accuracy in the reproduction of a thread profile of desired outline form upon the periphery of the grinding Wheel. In either case the mechanism embodies a minimum number of parts of simple and durable structural form which are capable of easy and quick assembly in functionally cooperative relation. It is also to be noted that, unlike prior mechanisms of this kind, the stylus and template outline with which it cooperates are completely enclosed within the tool slide housing so that the accumulation of foreign matter on these parts cannot impair the accurate operation of the wheel dressing tool. The embodiment of our invention disclosed in Figures 1 to 6 of the drawings provide an automatic wheel dressing unit of minimum overall dimension which may be mounted on the dresser slide of a grinding machine in the manner above explained to position the dressing tool in accordance with the helix angle of the thread grinding wheel so that said tool will properly and accurately dress the wheel profile.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In wheel dessing mechanism, a housing, a tool slide carriage, means for mounting said carriage within the housing for reciprocating motion longitudinally of the housing, a bracket transversely positioned within th housing on one end of the carriage and fixed thereto, guide means on the bracket spaced from and extending transversely across the carriage, a tool carrying slide, and anti-friction bearing units between said slide and the carriage and guide means, supporting said slide for reciprocating movement on the carriage in a path substantially at right angles to the path of reciprocation of said carriage.

2. Wheel dressing mechanism defined in claim 1, and a stylus carried by said slide, a stationary template mounted in the housing, a pin fixed to the slide, and spring means mounted on said bracket coaoting with said pin to yieldingly urge said stylus into coaoting engagement with the template.

3. The wheel dressing mechanism defined in claim 1, and a wheel dressing tool fixed to one end of said slide exteriorly of the housing, the

10 other end of said slide having a recess, a stationary bar mounted in the housing extending longitudinally above the carriage and having a tem-' plate part at one end positioned in said recess of the slide, and a stylus carried by the slide and coaoting with said template part.

4. In combination with the dresser slide of a grinding machine, wheel dressing mechanism mounted thereon for movement to and from operative position with respect to a grinding wheel, said mechanism including a housing, a tool carrying slide and actuating means in the housing to impart a compound movement to said slide in paths substantially at right angles to each other, and manually adjustable means on the housing coaoting with means on the dresser slide, to adjustably position the housing, tool slide and slide actuating means relative to the dresser slide, and initially position the dressing tool with respect to the peripheral profile of a grinding wheel.

5. In a wheel dressing mechanism, a rectangular housing, a carriage plate of substantially uniform thickness mounted within said housing on the bottom wall thereof for reciprocating motion in a plane substantially parallel with said housing wall, an actuating member journalled in the bottom wall of the housing and means operatively connecting said member with the carriage to reciprocate the latter, a tool slide, means extending across the upper surface of the carriage plate anddirectly supporting the tool slide thereon in a plane normal to the path of movement of the carriage, and means for reciprocating the tool slide in said plane, including coaoting parts fixed respectively to said tool slide and housing.

6. The wheel dressing mechanism defined in claim 5, in which a bracket is fixed to the carriage plate and anti-friction guide means is interposed between said bracket and the tool slide.

JAMES G. HARPER. CECIL W. HOPKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 672,337 Stanley Apr. 16, 1901 1,592,076 Bugbee July 13, 1926 2,294,008 Turrettini Aug. 25, 1942 2,317,411 Seyferth Apr. 27, 1943 2,397,503 Rauch Apr. 2, 1946 

